We are experiencing a fairly concerning issue with our 2013 GS350. Intermittently, when attempting to suddenly accelerate, but not to WOT the vehicle does nothing. In other words, imagine traveling at 30mph and you attempt to move ahead of traffic by depressing the accelerator noticeably further than it is currently depressed, but not quite to full wide open throttle and nothing happens. The expectation is that the car would immediately respond and accelerate. However, in my case the car does nothing for one or more seconds before eventually responding. This type of delay is extremely dangerous especially when attempting to change lanes or otherwise move out of the way of oncoming traffic or other obstacle.

There is on check engine light, no engine vibration, basically no obvious mechanical or electrical symptoms. I have tried different fuel and replace air filter. It seems unlikely (at least to me) that this would be an injector issue since my expectation is that the throttle position sensor and injector feedback to the computer should be smart enough to realize that they are out of sync (i.e. If pedal is at 70% and injector is not moving any fuel there must be a problem) and result in an error and/or check engine light.

Because the issue appears intermittent, at least so far, it is very hard to reproduce the problem and diagnose.

Any thoughts?

 

When you say "responding" - are you referring to it downshifting, rpms going up, or both? Almost sounds like your car isn't downshifting when needed.
What about driving in manual mode? That would isolate the downshifting issue.

 

How many miles? Has the fuel filter been replaced?

 

I'm saying that when I press the gas pedal quickly to a new increased position, nothing changes. No RPM increase, no downshift, nothing. It is like I didn't change the pedal position at all. My immediate thought is that the TPS is not seeing that I am changing the throttle position. However, if that was the case, I would think the issue would be more easily reproducible. If I gradually try to increase the pedal position things work without hesitation. Unfortunately, gradually increasing the throttle may not be enough to get me out of harms way fast enough.

 

Approximately 85,000 miles. All filters and fluids changed at 50,000 (as well as recent oil changes, etc).

 

Fuel pump going Bad?

 

I second this... probably worth a look. Or fuel filter faulty... allows enough flow for slow acceleration but for a quick spurt, it's too restricted.

Why'd you change the fuel filter at 50K, and was it performed at the dealer or an independent? OEM or replacement parts?

 

Noticed any of these? The Car hard to start for a moment like it was out of gas for a second or two?
A whining or humming noise from the Tank in the back seat?
Any jerkyness on hard floored acceleration?

Also have you scanned the ECU? Sometime there are Codes stored that did light up the Check Engine light.

 

Do you have RWD and what's the mileage? There is a fuel pump recall not sure if your car is impacted.

Its hard to pinpoint such a problem as it's intermittent and probably super frustrating...however, try disconnecting the battery for 10min and see if the problem continues to happen. To me, it sounds like there might be an ECU issue potentially with the throttle/pedal/sensors.

 

There is a recall for fuel pump.